<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
    <style>
      .progress {
        height: 25px;
        width: 400px;
        border-radius: 15px;
        background-color: #272425;
        border: 3px solid #272425;
        box-sizing: border-box;
        margin-bottom: 30px;
      }
      .inner {
        width: 50%;
        height: 20px;
        border-radius: 10px;
        text-align: right;
        position: relative;
        background-color: #409eff;
        background-size: 20px 20px;
        box-sizing: border-box;
        transition: all 1s;
      }
      .inner span {
        position: absolute;
        right: -20px;
        bottom: -25px;
      }
    </style>
  </head>
  <body>

    <div id="app">
    <div class="progress">
      <div class="inner" :style="{ width:percent }">
        <span>{{ percent }}</span>

      </div>

    </div>

    <button v-on:click="percent='25%'">设置25%</button>

    <button v-on:click="percent='50%'">设置50%</button>

    <button @click="percent='75%'">设置75%</button>

    <button @click="percent='100%'">设置100%</button>

  </div>

    <script src="https://cdn.jsdelivr.net/npm/vue@2/dist/vue.js"></script>

    <script>
        const app = new Vue({
            el:'#app',
            data:{
                percent:'50%'
            }
        })
    </script>
  </body>
</html>
